Sedimentology ESCI 332

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Sedimentology (ESCI 332) Clastics Dr. John
Anderson and TA Jason Francis First 7 weeks
of semester (minus 3) Me Julia Smith Wellner
Room 203F, jksmith_at_rice.edu, x2686 First
week of class, two weeks in February Carbonates
Dr. André Droxler and TA Michelle Shearer
Last 7 weeks of semester Schedule is subject to
change!
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Lab Fridays 1-4 pm Taught by the TAs No
lab this week Fieldtrips Several short trips
throughout the semester! Grades Lab grade goes
into overall grade Clastics portion will have
two take-home, essay exams More about
Carbonates grading later
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Books None, notes handed out in class for
Clastics More on Carbonates later Any
questions on logistics?
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Introduction to Facies Concepts What is
sedimentology? Scientific study of the
classification, origin, and interpretation of
sediments and sedimentary rocks. Physical,
chemical, and biologic properties of sediments
and sedimentary rocks. What is stratigraphy? Sci
ence of rock strata. Age relationships of
strata, successions of beds, local and worldwide
correlation of strata, and stratigraphic order
and chronological arrangement of beds in the
geologic column.
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Who uses sedimentology and stratigraphy? All
types of geologists! paleoceanographers,
geochemists, paleontologists structural
geologists glacial geologists, sea-level
change studies hydrologists, petroleum
geologists--define units in subsurface Need
to know facies associations...
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Walthers Law (1894) Johannes Walther
pioneered the study of modern environments as a
tool for interpreting sedimentary strata. The
various deposits of the same facies area and
similarly the sum of the rocks of different
facies areas were formed beside each other in
space, but in crustal profile we see them lying
on top of each other. i.e., Conformable
vertical successions of strata also occurred in
laterally adjacent environments. This does not
mean that any vertical succession will always
reproduce the horizontal succession of
environments, but that only those facies now
forming side by side could be superimposed
vertically. (adapted from Middleton, 1973)
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Lateral and vertical facies relationships
adapted from Van Wagoner et al., 1990
http//www.uga.edu/strata/sequence/parasequences.
html
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Why is knowing the facies relationship so
important? Often, geologists work in the
subsurface, need to define the shape and lateral
extent of sedimentary units.
Meandering river, dip-aligned
Coastal barrier, strike-aligned
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How do we define facies and interpret
depositional environments? Direct
Indicators fossils, including trace
fossils grain size distributions sedimen
tary structures mineralogy of
grains Indirect Indicators electric log
shapes high-resolution seismic
data Biofacies facies defined mainly with
paleontologic information Lithofacies facies
defined mainly with sedimentologic
criteria Seismic Facies facies defined mainly on
seismic data
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Each of these factors is non-unique and a
meandering river can have the same grain size as
a coastal barrier. Certain fossils are unique to
a given environment, but cant count on finding
these. Therefore use multiple criteria use
the vertical succession of characteristics to
define the facies Grain size and sedimentary
structures provide evidence of how the grains
were transported and deposited. It is another
step to interpret the environment of deposition.
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References used throughout for Class 1 332
notes from Anderson Principles of
Sedimentology and Stratigraphy (3rd Edition),
Boggs Principles of Sedimentology, Friedman and
Sanders